Process of making alumina and by-products.



PATENTED SEPT. 29;.' 90s.-

L. R. KEOGH. raocass OF MAKING ALUMINA'AND BY-PBODUGTS.

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APPLIOATION FILED JAN. 31 1903.-

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PATBNTED $31 1.29, 1903 L. R. KEOGH. Y 7 PROCESS 0 MAKING ALUMINA ANDBEE-PRODUCTS? APPLICATION FILED JAN. 811 i903.

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mac-mums vs ice. 740,364.

UNITED STATES Patented September 29, 1903.

PATENT OFFICE.

LUCIUS R. KEOGH, OF HAMILTON, CANADA.

SPECIFICATION forming part of Letters Patent No. 740,364, datedSeptember 29, 1903.

Original application filed August 13, 1902,. Serial No. 119,602. Dividedand this application filed January 31, 1903. Serial No, 141,280. (Nospecimens.)

of which the following is a full, clear, and exis act description, thisbeing a divisionof the application for Letters Patent of the UnitedStates filed by me August 13, 1902, Serial No. 119,502.

The object of the invention is to provide a new and improved process forthe manufacture of alumina and by-products, such as hydrochloric acid,sodium sulfate, sodium aluminate, sodium carbonate, and other substancesthat may be contained in clay, kaolin,

2o bauxite or other aluminous ores, sulfate of aluminium or other'aluminious materials to be treated, and sodium chlo'rid.

The process consists, essentially, in mixing sulfate of aluminium withsodium chlorid and some water to form a thick pulp, then heating thelatter and passing steam into the pulp to form a mixture of alumina andsodium sulfate and to evolve gaseous hydrochloric acid with steam, andfinally separating the s0-.

dium sulfate from the alumina.

In carrying out the process I prefer to use an apparatus such as shownin the accompanying drawings, forming part of this specifi-. cation, inwhich similar characters of reference indicate corresponding parts inboth views.

Figure 1 is a sectional side elevation of the apparatus for treatingcomparatively pure sulfate of aluminium, and Fig. 2 is alike view 46 oftheapparatus for treating impure sulfate of aluminium;

The apparatus shown in Fig. 1 consists, essentially, of a vessel A,arranged in a brickwork B and heated from the products of com- 5 bustionof the burning fuel held on the grate C of the furnace D, carrying asteam-boiler E. The brickwork is provided with an outlet-flue B. Thevessel A is connected by a pipe F with a condensation-chamber G, and

particularly pure.

In detail I proceed as follows: Sulfate of aluminium, preferablyhydrated sulfate of' aluminium or hydrated acid sulfate of aluminium, ofthe formula Al (SO,) .16H O and sodium chlorid in a quantity equivalentchemically to the sulfuric acid contained in the sulfate of aluminiumare thoroughly mixed with some water to form a pulp, which is placed inthe vessel A and gradually heated therein to about 200 to 300centigrade, and at the same time steam is passed into the pulp by thepipes H, so that hydrochloric acid is formed, which passes with thesteam through the pipe F to the condensation-chamber Gto be condensedtherein, while alumina and sodium sulfate settle in the vessel A and areremoved from the same to suitable washingtanks to dissolve the sodiumsulfate out of the alumina. In case the acid sulfate of aluminium havingsixteen molecules of water of hydration is treated as described then the,chemical reaction that takes place in the vessel A is as follows: Al(SO,) .16H O+(iNaGl:-'

2 A101,. SE20) 3Na,so,+ 4H,o.

'of alumina as free from impurities as can readily be obtained; but forthe preparation of the hydrated alumina in the first stage of theprocess, as well as for the preparation of sodium aluminate or sodiumcarbonate, it is not essential that the sulfate of alumina be Thesulfate of alumina may be treated in two ways, according to the productsdesired to be formed and'according tothe purity of the said sulfate. Ineither case it is first mixed with the sodium chlorid, which I prefer touse as pure as can be conveniently obtained, for more or less calciumsulfate or potassium chlorid is apt to be pres- 50 into the vessel Aextend the steam-pipes H,

cut and to affect the quality of the products :00

formed by giving rise to potassium sulfate, potassium carbonate, andcalcium chlorid or calcium sulfate in the products. The sodium chloridis added in a quantity equivalent chemically to the sulfuric acidcombined with the alumina and also contained in the impurities presentin the sulfate of aluminium, such assulfatesofiron,and thesodiumchloridand the sulfate of aluminium, together with the impurities containedtherein, are thoroughly and intimately mixed. This may be done toadvantage by adding the sodium chlorid to the sulfate of aluminium insolution just before evaporation is completed or by mixing the twotogether with a limited quantity of water and evaporating to such adegree of dryness as will enable the mixture to be readily subjected tothe next stage in the vessel A; but care must be taken that thetemperature does not rise above about 100 centigrade during this stageof the process. The evaporation referred to may be accomplished inshallow leaden pans I, set in the outlet-flue B,to be heated by thewaste heat from the fire-box D. The mixture of sodium chlorid andsulfate of aluminium is then shoveled-into the vessel A to be treated asdescribed. V

In case the sulfate of aluminium is impure the mixture must bethoroughly mixed with a sufi'icient quantity of carbonaceous matter,such as charcoal-dust or coal-dust, to reduce all or a suflicientportion of the sulfates formed to sulfids. The amount of thecarbonaceous matter is calculated and added during the evaporation tothe mixture in the leaden pans, or it may be added afterward and groundup with the mixture of sodium chlorid and sulfate of aluminium beforethis mixture is placed into the vessel A The reduced sulfate of sodiumshould be at least chemically equivalent to the alumina present and thecarbonaceous matter should be sufficient for the purpose of itsreduction.

It is understood thatmore or less steam is passed through the pipe Hinto the vessel A,

according to the amount of combined water in the sulfate of aluminium,it being understood that the less of such water the more steam isrequired until all the hydrochloric acid is expelled.

In case impurities, such as sulfates of iron, are in the sulfate ofaluminium then the apparatus shown in Fig. 2 is preferably employed,which apparatus consists of a vessel A arranged in the brickwork Bhaving an outlet-flue B and the said vessel A is heated by the productsof combustion from the burning fuel on a grate C in a fire-box D, havinga steam-boiler E for supplying steam by the pipes H to thereverberatory-furnace hearth J, arranged in the brickwork B between thefire-box D and the vessel A A pipe F connects the vessel A with acondensation-chamber G, and the flue B connects by valved branch pipes BB with combustion-chambers K and K. The reaction in the vessel A inaddition to thatoccurring in the vessel A, is as follows:

The hydrated chlorids, the aluminium, and all iron, if any, are thendecomposed as follows, (by the action of heat in the vessel A When thesulfate of aluminium is impure and it is desired to remove the ironoxid, then the resultant mass from the vessel A is transferred to thereverberatory furnace J, in which the temperature of the mass is raisedto a red heat and into which furnace jets of steam are introduced by thepipes H to come in contact with the mass whenever required. Thecarbonaceous matter present at the temperature mentioned reduces sulfateof sodium to sulfid of sodium, which, with oxid of iron in the presenceof alumina and steam, forms sodium aluminate and sulfid of iron. Thusshowing the case where single equivalents of iron and alumina werepresent and excess of carbon was used. Too free access of steam or airat this stage tends to oxidize the sulfids formed.

in case there be any alumina at this stage free to combine with thecaustic soda. It is not necessary, however, to reduce all the sulfate ofsoda to sulfid, but only so much thereof as will be chemicallyequivalent to the alumina present. Now the mixture of sodium aluminateand impurities, sulfid of iron, &c., is lixiviated and the aluminate ofsoda and excess'of caustic or of sodium sulfate, if any, are recovered.The alumina may now be precipitated from this solution in hydrated formin any of the ways usually employed in making alumina by means of sodiumaluminate; but it is best, too, if the caustic be in excess and when itis not desired to use the caustic over again to precipitate the solutionby means of carbondioxid gas, thus forming carbonate of soda, as well ashydrated alumina, both of which can now be recovered in any of the usualways in common use in the art. If the sodium sulfate be in excess, itcan be removed by crystallization before precipitation .of the alumina.

The carbon dioxid needed can be obtained from the gas formed in reducingthe sulfate of sodium to sulfid of sodium by means of the carbonaceousmaterial used in the charge.

The sulfureted hydrogen formed in the f urnace may be ignited in thecombustion-chambers K K to sulfur-or to sulfur dioxid and recovered. Anysulfid of sodium remainingin solution may be got rid of bycrystallizing. the carbonate of soda from the lye, which should beconcentrated by evaporation after the precipitated alumina is removed.

It is understood that other substances besides those described may beused andallied reactions may take place without deviating from myinvention. For instance, basic sulfates-of aluminium, also anhydrousacid sulfate of aluminium, may be used with steam, and sodium chloridand chlorid of potash may be used instead of chlorid of sodium.

Sulfates of iron and sodium chlorid may be used to form hydrochloricacid, sodium sulfate, and oxid of iron. Magnesium sulfate and sodiumchlorid may be employed with water of crystallization or steam to formsodium sulfate, magnesium oxid, and hydrochloric acid.

Having thus. described my invention, I claim as new and desire to secureby Letters Patent 1. The herein described process for the manufacture ofalumina and byproducts,

manufacture of alumina and by: products,

which consists in admixing together sodium chlorid, water, and aluminiumsulfate contaminated with iron sulfate, then adding carbon and heatingthe admixture to ared heat 7 in the presence of steam, thereby producinga mixture of sodium aluminate and iron sulfid, lixiviatingthe mixture ofsodium aluminate and iron sulfid, and precipitating the sodium aluminateand iron sulfid from the lixiviating solution.

3. The herein described process for the manufacture of alumina andby-products, which consists in admixing together sodium chlorid, Water,and aluminium sulfate contaminated with iron sulfate, then adding carbonand heating the admixture to a red heat in the presence of steam,thereby producing a mixture of sodium aluminate and iron sulfid,lixiviating the mixture of sodium alumi nate and iron sulfid,crystallizing out the soname to this specification in the presence ofthe subscribing witnesses.

LUGIUS R. KEOGH.

Witnesses:

ELIZABETH M. Knoen,

EDWARD R. VENATOR, MARY GILLEsBY.

